macrumors bot

With Apple having seeded the golden master build of OS X Mountain Lion to developers earlier this week, the company has locked in which Macs will support the forthcoming version of the operating system. While the machine requirements have been known for some time, the seeding of the final public release is a good time to remind users which machines will support Mountain Lion.

Ars Technica has more on Apple's decision, including discussion of why Apple has dropped support for some early 64-bit Macs that do support OS X Lion.

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Apple declined to tell us the reasoning behind leaving some of these models out of potential Mountain Lion upgrades, but we suspected it was related to an updated graphics architecture that was designed to improve OS X's graphics subsystem going forward. Our own Andrew Cunningham suspected the issue was related to graphics drivers, since the GPUs not supported under Mountain Lion had drivers that were written before 64-bit support was common.

Information included with the first Mountain Lion GM now corroborates the connection to 32-bit graphics drivers as the culprit. While Mountain Lion is compatible with any Mac capable of running a 64-bit kernel, the kernel no longer supports loading 32-bit kernel extensions (KEXTs).

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The report notes that some of the GPUs used in early 64-bit Macs were deprecated before 64-bit KEXTs were in common usage, and thus they were never upgraded from their original 32-bit KEXTs. With the affected machines now being a number of years old, Apple apparently decided that it was not worth investing the resources to upgrade those drivers to 64-bit in order to support OS X Mountain Lion.

macrumors regular

The ARS report seems to miss that EFI64 is required for Mountain Lion. While a Mac might have a CPU capable of 64-bit, it still might be running EFI32 and therefore won't be supported. No EFI64 means no 64-bit kernel which means no Mountain Lion.

macrumors 65816

Kinda pisses me off my mac pro may not get new osx, especially when there isn't a proper new mac pro. Apple ought not release osx that won't work on semi recent models. Pretty bad for customers. Could be an reason to upgrade... To a windows workstation

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With the affected machines now being a number of years old, Apple apparently decided that it was not worth investing the resources to upgrade those drivers to 64-bit in order to support OS X Mountain Lion.

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How much effort does it take to upgrade a kext/driver? I would guess less effort than working on "Game Center".

macrumors Pentium

The ARS report seems to miss that EFI64 is required for Mountain Lion. While a Mac might have a CPU capable of 64-bit, it still might be running EFI32 and therefore won't be supported. No EFI64 means no 64-bit kernel which means no Mountain Lion.

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First Unibody Macbooks released in 2008 had EFI32 only and yet can still run Mountain Lion.

macrumors 6502

The ARS report seems to miss that EFI64 is required for Mountain Lion. While a Mac might have a CPU capable of 64-bit, it still might be running EFI32 and therefore won't be supported. No EFI64 means no 64-bit kernel which means no Mountain Lion.

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I am running my Mac Pro 2,1 on Mountain Lion DP4. I'll be upgrading it when it is paid for.

You CAN run it on a Mac Pro 2,1 and earlier.

It took me a little time but really it is quite simple once you know what you are doing. You can PM me if you need any help.

macrumors Pentium

How much effort does it take to upgrade a kext/driver? I would guess less effort than working on "Game Center".

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Working on the low levels required for hardware access in a driver is where 32bit to 64 bit porting requires the most effort as often you're dealing with fixed width registries and can't simply "recompile" code into a 64 bit binary, you have to adjust types.

macrumors 601

People can't legitimately expect to receive the newest updates on machines that are 3+ years old.

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I'm pretty certain a few years ago people used to say "5+ years", by 2015 are people going to be saying "People can't legitimately expect to receive the newest updates on machines that are the last generation."

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